Light emitting device

Abstract

A light emitting device of an embodiment includes a light emitting element emitting near-ultraviolet light or blue light as exciting light; and a yellow color conversion layer including a yellow phosphor and a resin, the yellow phosphor represented by formula (1) and being capable of converting the exciting light to yellow light, the resin surrounding the yellow phosphor, the yellow color conversion layer containing the yellow phosphor at a volume concentration of at most 7%, the yellow color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface, (Sr 1-x1 Ce x1 ) a1 AlSi b1 O c1 N d1   (1) wherein x1, a1, b1, c1, and d1 satisfy following relations: 0<x1≦0.1, 0.6<a1<0.95, 2.0<b1<3.9, 0<c1<0.45, and 4.0<d1<5.0.

What is claimed is: 
     
         1 . A light emitting device comprising:
 a light emitting element emitting near-ultraviolet light or blue light as exciting light; and   a yellow color conversion layer including a yellow phosphor and a resin, the yellow phosphor represented by formula (1) and being capable of converting the exciting light to yellow light, the resin surrounding the yellow phosphor, the yellow color conversion layer containing the yellow phosphor at a volume concentration of at most 7%, the yellow color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x1 Ce x1 ) a1 AlSi b1 O c1 N d1    (1)
 
   wherein x1, a1, b1, c1, and d1 satisfy following relations: 0<x1≦0.1, 0.6<a1<0.95, 2.0<b1<3.9, 0<c1<0.45, and 4.0<d1<5.0.   
     
     
         2 . The device according to  claim 1 , wherein the formula (1) satisfies 0.05≦x1≦0.1. 
     
     
         3 . The device according to  claim 1 , wherein the exciting light is blue light, and when a chromaticity is expressed as (Cx, Cy) coordinates on a CIE chromaticity diagram, the device emits light with the chromaticity satisfying 0.30≦Cx≦0.48, 0.30≦Cy≦0.44. 
     
     
         4 . The device according to  claim 1 , further comprising:
 a green color conversion layer including a green phosphor and a resin, the green phosphor represented by formula (2) and being capable of converting the exciting light to green light, the resin surrounding the green phosphor, the green color conversion layer containing the green phosphor at a volume concentration of at most 7%, the green color conversion layer having a region whose cross section parallel to the light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
 
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11.   
     
     
         5 . The device according to  claim 1 , further comprising:
 a red color conversion layer including a red phosphor and a resin, the red phosphor represented by formula (3) and being capable of converting the exciting light to red light, the resin surrounding the red phosphor, the red color conversion layer containing the red phosphor at a volume concentration of at most 7%, the red color conversion layer having a region whose cross section parallel to the light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x3 Eu x3 ) a3 AlSi b3 O c3 N d3    (3)
 
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0.   
     
     
         6 . The device according to  claim 1 , wherein the yellow color conversion layer contains a green phosphor represented by formula (2), the green phosphor is capable of converting the exciting light to green light, and the sum of the volume concentrations of the yellow and green phosphors is at most 7%,
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11.   
     
     
         7 . The device according to  claim 1 , wherein the yellow color conversion layer contains a red phosphor represented by formula (3), the red phosphor is capable of converting the exciting light to red light, and the sum of the volume concentrations of the yellow and red phosphors is at most 7%,
   (Sr 1-x3 Eu x3 ) a3 AlSi b3 O c3 N d3    (3)
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0.   
     
     
         8 . The device according to  claim 1 , wherein the light emitting element is an LED. 
     
     
         9 . The device according to  claim 1 , wherein the yellow phosphor has a particle size of 1 μm to 25 μm. 
     
     
         10 . The device according to  claim 1 , further comprising:
 a green color conversion layer including a green phosphor and a resin, the green phosphor represented by formula (2) and being capable of converting the exciting light to green light, the resin surrounding the green phosphor, the green color conversion layer containing the green phosphor at a volume concentration of at most 7%, the green color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
 
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11; and   a red color conversion layer including a red phosphor and a resin, the red phosphor represented by formula (3) and being capable of converting the exciting light to red light, the resin surrounding the red phosphor, the red color conversion layer containing the red phosphor at a volume concentration of at most 7%, the red color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x3 Eu x3 ) a3 AlSi b3 O c3 N d3    (3)
 
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0,   wherein the red color conversion layer, the yellow color conversion layer, and the green color conversion layer are disposed in this order from the light emitting element.   
     
     
         11 . The device according to  claim 2 , wherein the exciting light is blue light, and when the chromaticity is expressed as (Cx, Cy) coordinates on a CIE chromaticity diagram, the device emits light with a chromaticity satisfying 0.30≦Cx≦0.48, 0.30≦Cy≦0.44. 
     
     
         12 . The device according to  claim 11 , further comprising:
 a green color conversion layer including a green phosphor and a resin, the green phosphor represented by formula (2) and being capable of converting the exciting light to green light, the resin surrounding the green phosphor, the green color conversion layer containing the green phosphor at a volume concentration of at most 7%, the green color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
 
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11.   
     
     
         13 . The device according to  claim 11 , further comprising:
 a red color conversion layer including a red phosphor and a resin, the red phosphor represented by formula (3) and being capable of converting the exciting light to red light, the resin surrounding the red phosphor, the red color conversion layer containing the red phosphor at a volume concentration of at most 7%, the red color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x3 EU x3 ) a3 AlSi b3 O c3 N d3    (3)
 
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0.   
     
     
         14 . The device according to  claim 11 , wherein the yellow color conversion layer contains a green phosphor represented by formula (2),
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11 and capable of converting the exciting light to green light, and the sum of the volume concentrations of the yellow and green phosphors is at most 7%.   
     
     
         15 . The device according to  claim 11 , wherein the yellow color conversion layer contains a red phosphor represented by formula (3),
   (Sr 1-x3 Eu x3 ) a3 AlSi b3 O c3 N d3    (3)
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0 and capable of converting the exciting light to red light, and the sum of the volume concentrations of the yellow and red phosphors is at most 7%.   
     
     
         16 . A light emitting device comprising: a light emitting element emitting near-ultraviolet light or blue light as exciting light; and
 a green color conversion layer including a green phosphor and a resin, the green phosphor represented by formula (2) and being capable of converting the exciting light to green light, the resin surrounding the green phosphor, the green color conversion layer containing the green phosphor at a volume concentration of at most 7%, the green color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
 
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11.   
     
     
         17 . The device according to  claim 16 , wherein the green color conversion layer contains a blue phosphor being capable of converting the exiting light to blue light and a red phosphor represented by formula (3):
   (Sr 1-x3 Eu x3 ) a3 AlSi b3 O c3 N d3    (3)
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0 and capable of converting the exciting light to red light, and the sum of the volume concentrations of the green and red phosphors is at most 7%,   wherein the exciting light is near-ultraviolet light.   
     
     
         18 . A light emitting device comprising: a light emitting element emitting near-ultraviolet light or blue light as exciting light; and
 a red color conversion layer including a red phosphor and a resin, the red phosphor represented by formula (3) and being capable of converting the exciting light to red light, the resin surrounding the red phosphor, the red color conversion layer containing the red phosphor at a volume concentration of at most 7%, the red color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x3 Eu x3 ) a3 AlSi b3 O c3 N d3    (3)
 
   wherein x3, a3, b3, c3, and d3 satisfy following relations: 0<x3≦0.2, 0.6<a3<0.95, 2.0<b3<3.9, 0.25<c3<0.45, and 4.0<d3<5.0.   
     
     
         19 . The device according to  claim 18 , further comprising:
 a green color conversion layer including a green phosphor and a resin, the green phosphor represented by formula (2) and being capable of converting the exciting light to green light, the resin surrounding the green phosphor, the green color conversion layer containing the green phosphor at a volume concentration of at most 7%, the green color conversion layer having a region whose cross section parallel to a light emitting surface of the light emitting element has an area larger than the light emitting surface,
   (Sr 1-x2 Eu x2 ) a2 AlSi b2 O c2 N d2    (2)
 
   wherein x2, a2, b2, c2, and d2 satisfy following relations: 0<x2≦0.2, 0.93<a2<1.3, 4.0<b2<5.8, 0.6<c2<1.0, and 6.0<d2<11   a blue color conversion layer including a blue phosphor and a resin, the blue phosphor being capable of converting the exciting light to blue light, the resin surrounding the blue phosphor,   wherein the red color conversion layer, the green color conversion layer, and the blue color conversion layer are disposed in this order from the light emitting element.   
     
     
         20 . The device according to  claim 19 , wherein the exciting light is near-ultraviolet light.